Internal pipe bender



Sept 27, 6 J. H. ANDERSON INTERNAL PIPE BENDER 5 Sheets-Sheet 1 FiledApril 15, 1964 E RN N rR vW W M W 1 n w m@ W 7 p 7, 1966 J. H. ANDERSON3,274,?

INTERNAL PIPE BENDER Filed April 15, 19 5 Sheets-Sheet FJ a I V Y /1 260282 288 284 -23s i 7: {O u mun 3: 294 L 1, 296 290 I s all N A 254 J M Qr/ A INVENTOR.

JAMES H. ANDERSON Z, g flM MJM A 1"! (JAN/53117.

Sept. 27, 1966 ANDERSON 3,274,317

INTERNAL PIPE BENDER Filed April 15, 19 4 5 Sheets-Sheet. 5

INVENTOR. JAMES H. ANDERSON BY 7 M mjwgczsw United States Patent3,274,817 INTERNAL PEPE FENDER James H. Anderson, 1615 Hilloclr Lane,York, Pa. Filed Apr. 15, 1964, Ser. No. 352,902 19 tClaims. (Cl.72--298) This invention relates generally to the art of pipe bending andmore specifically to a new and improved method and apparatus for bendingpipes, tubes and like structure.

Prior art structures for bending pipes and the like have generally beendesigned to operate on the exterior of the pipe to deform the walls bythe application of external pressure. This kind of structure, especiallythe type designed to bend pipes of large diameter, is expensive, bulkyand usually limited in use to situations where the exterior of the pipebeing bent is readily accessible to the machinery.

A further defect in the prior art pipe bending devices is theintentional or inadvertent wrinkling of the pipe in the area of the benddue to in many instances the lack of interior support for the walls ofthe pipe when external pressure is applied thereto. Apparatus in theform of flexible mandrels, such as shown in Ballard, 2,984,284, andAvera et al., 3,109,477, do provide an interior support for the pipeduring the bending operation as performed by an external pipe bendingdevice. Although these devices are very successful in their objectives,they do entail additional operation and equipment expense in the bendingoperation.

It is, therefore, an object of the present invention to provide a methodand apparatus for bending pipe which avoids the above-stated defects ofthe prior art by providing an apparatus which effects a bending of pipesand tubular objects entirely from the interior surfaces thereof.

It is another object of this invention to provide a pipe bending devicehaving a mandrel-type member engageable with the interior of a pipe tointernally support the pipe during bending for achieving a smoothwrinkle-free bend in the pipe.

It is a further object of this invention to provide a pipe bendingdevice having an internal pipe engaging member which may be located inremote, relatively inaccessible portions of the pipe to effect a bendingthereof.

It is still another object of this invention to provide an internal pipebending device which bends pipe where the exterior portions thereof arenot accessible for the conventional bending operation.

These and other objects will become more apparent to those skilled inthe art by reference to the following detailed description when viewedin light of the accompanying drawings in which like numerals indicatelike parts throughout the figures thereof and wherein:

FIG. 1 is an elevational view in section of a pipe bending apparatusembodying the features of the present invention;

FIG. 2 is a view similar to FIG. 1 showing the apparatus thereof at thetermination of its bending operation;

FIG. 3 is a vertical sectional View of the apparatus of FIG. 1, the viewbeing taken along the lines 3-3 thereof;

FIG. 4 is an elevational view in seciton of a portion of a modifiedapparatus embodying the features of the invention;

FIG. 5 is an elevational view in section of another pipe bendingapparatus embodying features in accordance with the invention;

FIG. 6 is an elevational view in section of still another pipe bendingapparatus embodying features of the present invention; and

FIG. 7 is an elevational View in section of a portion of ice yet anotherpipe bending apparatus in accordance with the present invention.

This invention consists of two gripping members for engaging the innersurface of a pipe at axially spaced points and means for displacing thegripping members angularly with respect to one another. This provides astretching or compressing of a circumferential portion of the wall ofthe pipe to induce a bend therein. In certain embodiments of theinvention means are provided for alternately lengthening and shorteningthe distance between the gripping members while they are first in agripping and then in a non-gripping state to provide for a crawlingtravel of the gripping members and means through the interior of thepipe.

Referring to FIG. 1 of the drawings there is shown an internal pipebending apparatus 16, positioned in the interior of a pipe 18. Theapparatus consists of a pair of circular gripping members 20 and 22,that are disposed in spaced relationship to one another and connectedtogether by a tension link 24 and an expansible and contractible workinglink 26.

Each of the gripping members 20 and 22 is substantially identical inmirror asymmetry so that the following description will be directed toone of said members. The gripping member 20 is formed with a cylindricalbody 28 having inner and outer disc shaped walls 30 and 32 respectively,connected together by a cylindrical web 34. The web is of a smallerdiameter than that of the Walls 30 and 32 to form an annular recess orchamber 36 around the periphery of the body 28. An expansible sealingring 38, preferably formed of elastomeric material, is slidably disposedbetween the outer ends of the walls 30 and 32 to seal the open end ofthe chamber 36. An annular split ring 40, fabricated of a relativelyhard material such as steel or the like, is positioned around thesealing ring 38 and provides an expandable backing member therefor. Thering 40 is formed with slots 42 (FIG. 3), which furnishes the expansiblecapability therefore, while an annular gripping ring 44, is disposed ina recess around the split ring 40. The ring 44 is fabricated from orfaced with a material harder than the material of the pipes to be bent,and, in addition, said ring is provided with slots 46 (FIG. 3) to permitit to expand and contract. The inner wall 30 of the gripping member 20is formed with a port 48 that receives a flexible conduit 50 to providehydraulic communication between the chambers 36 in the gripping members20 and i 22. The wall 32 of the gripping member 22 is provided with aport 52 communicating with the chamber 36 and which is connected by aflexible conduit 54 to a source of hydraulic pressure, not shown, foralternately supplying and bleeding hydraulic fluid to and from thechambers.

In the operation of the gripping members 20 and 22, hydraulic fluidunder suitable pressure is supplied to the chambers 36 through thesupply conduit 54 and conduit Stl, thereby expanding the sealing rings38 and split rings 40 to force the rings 44 into gripping contact withthe interior of the pipe 18. The gripping surface of the rings 44 isslightly roughened by pit marks or grooves to provide the greatestpossible frictional holding force for the gripping members.

The tension link 24 is pivotally mounted between lugs 56 provided on theinner surface of the walls 30 to conmeet the gripping members 20 and 22together at a point spaced from the common symrnetrioal axis thereof.The link 24 consists of a pair of oppositely threaded rods 55 and 57having one end CUIlIIEC'lICld to the lugs 56 and the other end connectedtogether by a collar 58 having oppositely threaded halves therein tomate with the threads on the rods. Rotation of the collar 58 withrespect to the rods 55 and 57 provides a lengthening or shorteningadjustment of the rods with respect to the collar depending on thedirection of rotation.

The working link 26 of the apparatus is pivotally connected to lugs 60formed on the inner surfaces of the walls 30 at a point spaced from thecommon axis of symmetry of the gripping members and diametricallyopposite the position of the tension link 24. The working link consistsof a cylinder 62 that has a closed end connected to the lug 60 of thegripping member 22, while Ia piston and piston rod 64 are slidablydisposed therein, with the rod being connected to the lug 60 of thegripping member 20. The area of the cylinder 62 between the closed endand the piston 64 defines a pressure chamber 66 While the open end ofthe cylinder has secured thereto an inwardly projecting flange 68 tolimit the movement of the piston 64 in one direction of movement in thecylinder. A piston sealing ring 70 is mounted on the head of the piston.A port 72 formed in the closed end of the cylinder 62 receives a conduit76 which is connected to a chamber 74 formed in the central portion ofthe gripping member 22. The chamber 74 is formed with a port 80 that hasa conduit 78 disposed therein for communicating with a source ofpressure supply (not shown).

Referring to FIG. 2 the apparatus is shown in an exaggerated conditionfor bending the pipe 18. The apparatus is positioned in the pipe 18 Withthe gripping members 20 and 22 engaging the inner-periphery of the pipeat spaced points. The piston and rod 64 are actuated upon the deliveryof fluid to the chamber 66 by way of conduit 78, chamber 74 and conduit76, to force the piston towards the flange 68. The movement of thepiston and rod 64 angularly displaces the gripping members 20 and 22with respect to one another by forcing the upper portions of the membersapart while the tension link 24 retains the lower portions of thegripping members in their initial spaced relation. The gripping members20 land 22,

being so disposed and in frictional engagement with the interior surfaceof the pipe, will stretch the upper wall' portions of the pipe,producing a bend in the pipe (FIG. 2). Deformation of the pipe, becauseof the normal stress transmission characteristics of homogenousmaterial, as well 'as the tension and bending stresses imposed onadjacent portions of the structure, will be distributed in decreasingquantities from the point sources of stress to produce a relativelysmooth and even bend in the pipe.

In the event that the strength of the pipe material or the thickness ofthe walls thereof exceeds the holding capability of the gripping membersshown in FIGS. 1 through 3, or the pressure required to hold or gripexceeds the circumferential strength of the pipe at single grippingpoints, additional gripping units may be employed as shown in FIG. 4.The gripping means 122 in this embodiment is formed with a pair ofadjacent chambers 136 and 137 and which are connected to independentsources of pressure (not shown) by means of flexible conduits 153 and154. The chambers 136 and 137 are provided with sealing rings 138 andsplit rings 140 and 141, as in the embodiments of FIGS. 1 through 3.Gripping rings 144 and 145, respectively are positioned in recesses inthe split rings. Although the operation of the device shown in FIG. 4 isthe same as the previous embodiment, the area of contact and thereforethe frictional force or resistance to movement of the gripping member isincreased through the provision of the additional gripping ring 145. Theuse of additional gripping rings offers a further advantage in that thegripping force may be graduated with respect to the area of stressgenerated by the bending of the pipe. In the embodiment of FIG. 4, thisadvantage is brought about by placing the larger contact area of thegripping ring 144 closer to the area of bending stress in the pipe thanthe smaller contact area of the gripping ring 145 so that thecircumferential stress generated in the pipe by the expansion of thegripping ring is lower proximate the point of bending stress. The

circumferential stress from the gripping rings may also he graduated bysupplying lower hydraulic pressure to the chamber 136 than that suppliedto the chamber 137.

Although the number of chambers in each gripping member can obviously bevaried, the length of the structure would be limited dependent upon itspassage through the bends of the pipe because of the rigid connectionbetween the adjacent chambers. It is therefore readily conceivable thatthe chambers may be formed as individual units connected to one anotherby suitable fasteners, such as bolts or the like. The fasteners may beloosened by extension wrenches or the like during the passage of thedevice through the pipe to allow angular displacement between theadjacent units and tightened for rigid connection between the unitsduring the gripping and bending portion of their cycle.

In FIG. 5 there is shown a further variation of the bending apparatuswherein corresponding parts have been identified by the same referencenumerals, only using the next higher series. In this embodiment theprimary distinction is in the working link 226 which consists of a screwjack having a pair of oppositely threaded rods 282 and 284 and having anend thereof pivotally connected to the lugs 260 on the gripping members220 and 222. The free ends of the rods are connected together by asleeve 286 which is threaded over said ends in such a manner thatrotation of the sleeve in opposed directions will lengthen or shortenthe working link 226. The sleeve 286 is formed with teeth 288 thatcooperate with a link drive chain 290 disposed around a portion of theperiphery thereof. A motor 292, connected to a suitable source of power(not shown) is mounted in a bore 294 centrally formed in the grippingmember 22. The motor 292 has, extending therefrom, a spline power shaft296 which has a sprocket 298 mounted thereon for rotation therewith. Theteeth of the sprocket 298 engage the links of the drive chain 290 tosupply driving power to the sleeve 286.

In operation the apparatus is positioned in the pipe with the grippingrings 244 engaging the interior walls thereof and, power is supplied tothe motor 292 to drive the sprocket 298 and chain 290 causing rotationof the sleeve 286 and extension or retraction of the working link 226and a resulting bending of the pipe. Since the link is not concentric tothe centerline of the pipe, the extension or retraction of the link willproduce a greater tension in the upper wall than in the lower wall ofthe pipe thereby exceeding the yield point of the upper pipe wall beforeexceeding that of the lower pipe wall when the force is great enough. Inthis manner, the apparatus may be used to accomplish bending without theuse of a tension link as in the preceding figures. Obviously, severalchain drives may be utilized to increase the operating force of theapparatus or the number of screw jacks or working links 226 could beincreased and powered by suitable drive arrangement to increase theamount of force available for the bending operation.

The use of a single, eccentric link to connect the two gripping membersof the device also provides a particular advantage since the bendingapparatus can then be made to travel, under its own power, to the pointin the pipe where same is to be bent. This can be achieved by providingseparate pressure sources for the gripping members 220 and 222respectively, and with the apparatus of FIG. 5, first applying pressureonly to the gripping unit 222 then, operating motor 292 to extend theworking link 226 thereby moving the gripping member 220 along the pipeto the limit of the extension of the link 226, releasing the pressure inthe gripping member 222 while applying pressure to the gripping member220, then retracting the link 226 by counter-rotation of motor 292 topull the gripping member 222 towards the gripping member 220 andrepeating this operation to providefor a crawling or walking type ofmovement of the apparatus along the pipe. This procedure could obviouslybe atomatized through the use of proper electrical and hydrauliccontrols and limit switches so that the apparatus may be automaticallymoved to remote locations in a pipe string to perform a bendingoperatlon at that point even when the exterior of the structure isinaccessible. This crawling capability can also be utilized to provide abend at one point in a pipe, then automatically move to another point toperform a bending operation and so on to provide a bend in a pipe havinga large continuous radius.

In FIG. 6 there is shown a hydraulic pipe bending apparatus having thecrawling capability which consists of a piston cylinder combination inthe working link 326 as well as the tension link 324. The working link326 is essentially the same as that described for the embodiment of FIG.1 with the exception that an end plate 368 encloses the open end of thecylinder to form a pressure chamber 367 so that the piston 364 operatesbetween a pair of pressure chambers 366 and 367. Each of the chambershas connected thereto a pressure conduit 369 and 376, respectively,which in turn are connected to a suitable source of pressure, not shown.A seal 381 is provided in the plate 368 for engagement with the pistonrod to prevent the escape of any fluid from the chamber 367.

The tension link 324 includes a piston cylinder combination which isessentially identical to that of the working link 326. A cylinder 317,having a closed end connected to the lug 356 on gripping member 320 by arod 319, also is closed at the other end by a plate 321 to form chambers323 and 325 on opposite sides of a piston 327. A seal 329 is provided inthe plate 321 for the identical purposes as that described for seal 331in the working link 326. Chambers 323 and 325 are connected to suitablesources of pressure by conduits 331 and 333.

In operation, the apparatus is positioned within a pipe and fluid underpressure is supplied to chamber 366 through conduit 376 to extend theworking link 326 and thereby bend the pipe. During this operation, thepiston 327 may be disposed in one of several positions depending uponthe type of bend to be formed in the pipe. The piston may be locked inplace or it may be retracted by supplying pressure through flexibleconduit 333 to provide compression in the lower portion of the wall orit may be extended by supplying pressure through conduit 331 to extendthe tension link 324 simultaneously with the bending operation toprovide a wider radius bend in the pipe.

The crawling capability of the device is achieved by hooking theconduits 369 and 333 as well as the conduits 331 and 336 to the samepressure source or to pressure sources which act in unison and thenalternating the sup ply of pressure to first one side of the pistons andthen to the other. With the above hydraulic arrangement and withalternate actuation of gripping members, as described for the embodimentof FIG. 5, the apparatus will crawl through the pipe to a desiredlocation. Obviously, this type of power device may be adapted toautomatic operation as easily as the mechanical apparatus described inFIG. 5.

With reference to FIG. 7 of the drawings, a further variation of thegripping member of the invention is illustrated wherein partscorresponding to previous embodiments have been identified by the samereference numeral only using the next higher series. In this figure,three identical gripping units 315 are mounted as a unit on the end ofthe gripping unit 320, which gripping unit may form part of any of thepreviously described pipe bending structures. As was pointed out inconnection with the structures shown in FIG. 4, an increase in thenumber of gripping units increases the holding force of the grippingmembers without too great an increase in the cylindrical stress on thepipe where such increases are necessary. In this embodiment, the units315 are connected to the end unit 322 by bolts 335 fastened thereto bynuts 337. There is provided some degree of flexiblity in the mounting ofthe units by the interposition of conical spring washers 343 and 345under the heads of the bolts 335. The units are normally kept inabutting relationship to one another but may extend or deflect angularly to negotiate curves in the pipe when the apparatus is being movedtherethrough.

The above-described embodiments are, of course, illustrated merely toshow those skilled in the art, specific ways in which the presentinvention may be carried out to effectively and efficiently bend pipesor other tubular members and obtain relatively free and smooth areas ofbend in the pipes. It should also be obvious that the features of theparticular structures as set forth may be readily interchanged Withinthe basic concepts of the invention. It should, therefore, be understoodthat, within the scope of the appended claims, the invention may bepracticed otherwise than is specifically set forth. What is claimed asnew and is desired to be protected by Letters Patent of the UnitedStates is:

1. An apparatus for bending a tubular structure comprising grippingmembers positioned Wi-thin a tubular structure in axially spacedrelation to one another, means to actuate said gripping members toengage said tubular structure, a second means interposed between andconnecting said gripping members, said second means being operative toeffect angular displacement between said gripping members or stretchinga portion of the wall of said tubular structure to effect a bendtherein.

2. An apparatus in accordance With claim 1 wherein said second meansalso eifects axial displacement between said gripping members and saidactuating means is further adapted to actuate said gripping membersindependently of one another, said apparatus being movable through saidtubular structure by alternate actuation of each of said grippingmembers and corresponding alternate operation of said second means toprovide extending and retracting axial displacement between saidgripping members.

3. An apparatus for bending a tubular structure comprising:

a pair of gripping members positioned in a tubular structure in axiallyspaced relation to one another, means to actuate said gripping membersto conform to and grip said structure;

a second means interposed between and connecting said gripping members,and a link means interposed between and connecting said gripping membersand being spaced from said second means, said second means beingoperative to effect at least angular displacement between said grippingmembers for stretching a portion of the wall of said tubular structureto effect a bend therein.

4. An apparatus in accordance with claim 1 wherein said second meanscomprises:

at least one link pivotally connecting said gripping members in spacedrelationship to the axial centerline thereof;

and at least one extending means associated with said one link to effectaxial extension of that link, means to actuate said extending means toimpose an asymmetrical -force between said gripping members for pivotaldisplacement therebetween when both of said gripping members are ingripping engagement with the interior of said structure.

5. An apparatus in accordance with claim 4 wherein siad extending meanscomprises a hydraulic piston-cylinder combination interposed between andconnecting the ends of said link to provide extension thereof, andconduit means including a valve for selectively connecting at least oneside of said piston to a source of hydraulic pressure to selectivelyactuate said piston to at least extend said link.

6. An apparatus in accordance with claim 4 wherein said extending meanscomprises a rotary screw jack interposed between the ends of said linkand means to selectively rotate said screw jack to effect at least axialextension of said link.

7. An apparatus in accordance with claim wherein means are provided toselectively connect hydraulic pressure to both sides of said piston,whereby the supply of hydraulic pressure to alternate sides of saidpiston effects corresponding extension and retraction of said link.

8. An apparatus in accordance with claim 4 wherein a second linkpivotally connects said gripping members at a point transversely spacedfrom said one link.

9. An apparatus in accordance with claim 8 wherein extending means areassociated with said one link and said second link to effect axialextension and retraction of said links, and means to actuate saidextending means, actuation of one of said extending means aloneeffecting pivotal displacement between said gripping members and similaractuation of both of said extending means simultaneously effecting axialdisplacement between said gripping members.

10. An apparatus in accordance with claim 1 wherein said grippingmembers comprise at least one circular plug defining an annular chamberaround and open to the periphery thereof, annular resilient sealingmeans disposed to enclose and seal the outer periphery of said chamber,said sealing means being radially slidable in said chamber, an annularexpansible gripping ring disposed around said sealing means, conduitmeans including valves to selectively connect said chamber to a sourceof hydraulic pressure, the supply of hydraulic pressure to said chamberexpanding said seal and gripping ring into gripping contact with theinner periphery of said tubular structure, and means to selectivelyexhaust hydraulic pressure from said chamber, said gripping ring beingwithdrawn from gripping contact with the inner periphery of said tubularstructure when pressure is exhausted from said chamber.

11. An apparatus in accordance with claim 10 wherein the said grippingmembers comprise a plurality of said plugs in axially abuttingrelationship to one another, and means to connect said plugs together.

12. An apparatus in accordance with claim 11 wherein said means toconnect said plugs together includes resilient means to bias said plugsin abutting relationship yet provide a resilient angular displacementcapability between said plugs.

13. An apparatus in accordance with claim 11 wherein the axial Width ofsaid gripping ring for each of said plugs is successively larger instepped increments away from the plugs most proximate said second means.

14. An apparatus for bending a tubular structure comprising a pair ofaxially spaced gripping members positioned in and comformable to theinner periphery of a tubular structure along transverse planes thereto,said gripping members comprising:

(a) At least one circular plug defining an annular chamber around andopen to the periphery thereof;

(b) annular resilient sealing means disposed to enclose and seal theouter periphery of said chamber, said sealing means being radiallyslidable in said chamber;

(c) an annular expansible gripping ring around said sealing means;

(d) conduit means including valves to selectively connect said chamberto a source of hydraulic pressure; the supply of hydraulic pressure tosaid chamber expanding said seal and said gripping ring into grippingcontact with the inner periphery of said tubular structure;

disposed 8 (e) and means to selectively exhaust hydraulic pressure fromsaid chamber;

said gripping ring being withdrawn from gripping contact with the innerperiphery of said tubular structure when pressure is exhausted from saidchamber; and a second means disposed between and connecting saidgripping members and operative to provide at least angular displacementtherebetween comprising:

(a) at least one link pivotally connecting said gripping members anddisposed in spaced relationship to the axial centerline thereof;

(b) and at least one extending means associated with said link to effectaxial extension of that link, means to actuate said extendind means toapply an asymmetrical axially extending force to said gripping membersto thereby produce pivotal displacement therebetween when both of saidgripping members are in gripping engagement with the interior of saidstructure for stretching a portion of the wall of said tubular structureto effect a bend therein.

15. An apparatus in accordance with claim 14 wherein said extendingmeans comprises a hydraulic piston-cylinder combination interposedbetween the ends of said link to provide extension thereof, conduitmeans including a valve to connect at least one side of piston to asource of hydraulic pressure to selectively actuate said piston.

16. An apparatus in accordance with claim 14 wherein said extendingmeans comprises a rotary screw jack interposed between the ends of saidlink and means to selectively rotate said screw jack to effect axialextension and retraction of said link.

17. An apparatus in accordance with claim 15 wherein means are providedto selectively connect hydraulic pressure to both sides of said piston,the supply of hydraulic pressure to alternate sides of said pistoneffecting alternate extension and retraction of said link.

18. An apparatus in accordance with claim 14 wherein a second linkpivotally connects said gripping members at points transversely spacedfrom said one link.

19. An apparatus in accordance with claim 18 wherein extending means areassociated with said one link and said second link to effect axialextension and retraction of both of said links, and means to selectivelyactuate said extending means, the actuation of one of said extendingmeans effecting pivotal displacement between said gripping members andsimilar actuation of both of said extending means, simultaneously,effecting axial displacement between said gripping members.

References Cited by the Examiner UNITED STATES PATENTS 520,870 6/1894Winfield et a1 72-298 1,804,384 5/1931 Miller 72-298 2,371,393 3/1945Horrigan 72-392 3,109,477 11/1963 Avera et a1 72-466 CHARLES W. LANHAM,Primary Examiner. L. A. LARSON, Assistant Examiner.

1. AN APPARATUS FOR BENDING A TUBULAR STRUCTURE COMPRISING GRIPPING MEMBERS POSITIONED WITHIN A TUBULAR STRUCTURE IN AXIALLY SPACED RELATION TO ONE ANOTHER, MEANS TO ACTUATE SAID GRIPPING MEMBERS TO ENGAGE SAID TUBULAR STRUCTURE, A SECOND MEANS INTERPOSED BETWEEN AND CONNECTING SAID GRIPPING MEMBERS, SAID SECOND MEANS BEING OPERATIVE TO EFFECT ANGULAR DISPLACEMENT BETWEEN SAID GRIPPING MEMBERS OR STRETCHING A PORTION OF THE WALL OF SAID TUBULAR STRUCTURE TO EFFECT A BEND THEREIN. 